(1) Field of the Invention
The present invention relates to a communication system and a communication device, such as a portable telephone and a hands-free communication device, and to a communication method thereof.
(2) Description of Related Art
The following describes a hands-free communication system as an example of a conventional communication system with reference to drawings.
FIG. 1 is a block diagram showing a conventional hands-free communication system 1000.
This hands-free communication system 1000 comprises a portable terminal device 1010 and a hands-free device 1030. The portable terminal device 1010 is a portable telephone. The hands-free device 1030 is installed in an automobile and conducts communications over a telephone network by communicating with the portable terminal device 1010 that is brought into the automobile.
The portable terminal device 1010 includes the following elements: a terminal interface unit 1011 that functions as an interface for communication via a 16-conductor cable 1020; a microphone 1014 that collects the speech (voices) of a user of the portable terminal device 1010; a speaker 1015 that outputs the speech of the other person to whom the user talks on the portable terminal device 1010; a display unit 1016 that displays a telephone number and the like; and a terminal control unit 1013 that controls the terminal interface unit 1011, the microphone 1014, the speaker 1015, and the display unit 1016.
When this portable terminal device 1010 is set in normal mode and communicates with another telephone via the telephone network, the terminal device 1010 has the microphone 1014, the speaker 1015, and the display unit 1016 operate under the control of the terminal control unit 1013. In this normal mode, the user holds the portable terminal device 1010 in his hand and speaks with the other person who uses another telephone.
The hands-free device 1030 includes the following elements: an interface unit 1031 that functions as an interface for communication via the 16-conductor cable 1020; a microphone 1037 affixed on a rearview mirror of the automobile, for instance, to collect the speech of a driver; a speaker 1038 that outputs the speech of the other person to whom the driver talks through the hands-free device 1030; a display unit 1039 that displays a telephone number and the like; a control unit 1036 that controls the interface unit 1031, the microphone 1037, the speaker 1039, and the display unit 1039; and an input unit 1040 that includes operational buttons and gives an instruction to the control unit 1036 in accordance with operations on the operational buttons.
With this hands-free communication system 1000, the 16-conductor cable 1020 connects the terminal interface unit 1011 of the portable terminal device 1010 with the interface unit 1031 of the hands-free device 1030. In this way, the portable terminal device 1010 is connected to the hands-free device 1030 in a one-to-one relationship.
As soon as the portable terminal device 1010 and the hands-free device 1030 are connected to each other in this way, the portable terminal device 1010 switches its operational mode from the normal mode to the hands-free mode so that the user can speak over the terminal device 1010 without holding it in his hand. Hereafter, such communication is called “hands-free communication”.
The following describes an operation which is performed by the conventional hands-free communication system 1000 when the portable terminal device 1010 clears the normal mode and switches, together with the hands-free device 1030, to the hands-free mode.
FIG. 2 is a sequence diagram showing this operation of the hands-free communication system 1000.
As soon as the portable terminal device 1010 and the hands-free device 1030 are connected to each other via the 16-conductor cable 1020 (step S900), the portable terminal device 1010 clears the normal mode and switches to the hands-free mode to perform hands-free communication (step S902). At the same time, the hands-free device 1030 also switches to the hands-free mode (step S904).
Consequently, the hands-free communication system 1000 performs hands-free activation operation that activates the microphone 1037 and the speaker 1038 so that the user can perform the hands-free communication for calling another telephone or receiving a call from another telephone (step S906).
In more detail, when the portable terminal device 1010 receives a call while the terminal device 1010 and the hands-free device 1030 are set in the hands-free mode, the terminal device 1010 notifies the hands-free device 1030 of the reception of the call, so that the control unit 1036 of the hands-free device 1030 has the speaker 1038 output ringing sounds. When the control unit 1036 receives an instruction to answer the telephone from the input unit 1040, the portable terminal device 1010 and the hands-free device 1030 perform the aforementioned hands-free activation operation. This enables the driver (i.e., the user) to hear the speech of the other person on the line through the speaker 1038 and sends his own speech collected by the microphone 1037 to the other person so as to perform the hands-free communication.
On the other hand, when the driver operates the input unit 1040 to request the hands-free device 1030 to make a call while the terminal device 1010 and the hands-free device 1030 are in the hands-free mode, the control unit 1036 of the hands-free device 1030 notifies the portable terminal device 1010 of this request, so that the terminal device 1010 makes the requested telephone call to another telephone. When the telephone call is answered, the hands-free device 1030 and the portable terminal device 1010 perform the hands-free activation operation. As a result, the driver can conduct the hands-free communication.
The conventional hands-free communication system 1000, however, requires the user to perform a troublesome manual operation to connect the portable terminal device 1010 to the hands-free device 1030 with the 16-conductor cable 1020.
In addition, when the hands-free device 1030 and a plurality of the portable terminal devices 1010 are connected to one another with either a bus network or a wireless network with these devices 1030 and 1010 within a communicable range, then the hands-free device 1030 cannot specify, out of the plurality of portable terminal devices 1010, a portable terminal device 1010 with which the hands-free device 1030 should establish a communication link.